Low resistance reservoir development, as an unconventional oil and gas field, presents a complex formation mechanism, challenging development process, and an unclear understanding of the change in water cut during early-stage development. The Guantao III Up formation in Bohai C Oilfield is a low resistivity formation with low structural amplitude, complex lithology and small pore throat radius. The capillary pressure of the reservoir is large and affects the oil and gas charging. This paper presents the identification of factors contributing to high water saturation in low resistivity reservoirs through laboratory core experiments and NMR micro-analysis, as well as the determination of variations in reservoir water salinity within the same reservoir based on field sampling experiments. During the initial phase of C oilfield development, natural energy is predominantly utilized for reservoir exploitation. Due to the poor physical properties of the reservoir, early-stage production wells exhibit significant pressure differentials, leading to high mobility of primary water saturation in the reservoir and a lack of water-free recovery period. This stands in stark contrast to the evolution pattern of water cut observed in conventional edge water driven oil reservoirs during their initial development stages. This paper presents a comprehensive analysis of the early-stage water cut regularity in low resistance reservoir, drawing from both laboratory experiments and field production phenomena. The findings have significant implications for guiding the decision-making process regarding the development mode of low resistance reservoirs.